Fluid pump for delivering cooled working fluid in an engine cooling system

ABSTRACT

A fluid pump for delivering cooled working fluid in an engine cooling system includes a housing unit defining front and rear chambers, an inlet disposed upstream of a central region of the front chamber, an outlet disposed downstream of a surrounding region of the front chamber, a canister member dividing the rear chamber into stator- and rotor-side spaces for receiving a stator and a rotor, respectively, a hollow shaft which is rotated with the rotor to turn an impeller in the central region and which defines a passage, and an auxiliary conduit communicated with the inlet and the rear chamber so as to divert part of the working fluid to flow through the internal duct and the passage, thereby diffusing heat generated within the housing unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a fluid pump, more particularly to a fluid pump for delivering cooled working fluid in an engine cooling system.

2. Description of the Related Art

Use of fluid pumps in vehicle engine cooling systems in which tank water is pumped into a cooling conduit of an engine is well known. During operation of a fluid pump, the stator, internal control circuit and the like of the fluid pump also generate heat energy. Heat energy outside the stator can be dissipated by conduction or convection, but heat energy inside the stator accumulates gradually, so that the temperature inside the fluid pump is quite high, which may result in failure of the fluid pump and low dissipating efficiency of the fluid pump.

In order to address such drawbacks, there has been proposed that a fluid pump in which a cover is disposed to cover a canister for accommodating a rotary shaft and a rotor is formed with a plurality of holes that are in fluid communication with an interior chamber of the canister. Thus, some working fluid may flow into and out of the interior chamber to dissipate heat energy generated by a stator and a controller of the fluid pump. However, since the working fluid flows in and out through the through holes, the circulation of the fluid in the interior chamber is not steady and smooth, i.e., heated fluid in the interior chamber cannot readily flow out through the holes, while cooled fluid out outside of the interior chamber cannot readily flow into the filled interior chamber. Hence, heat energy inside the fluid pump cannot be dissipated effectively.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a fluid pump which can achieve good heat-dissipating efficiency.

According to this invention, the fluid pump includes a housing unit, a canister member, a fluid drawing mechanism, and an auxiliary conduit. The housing unit defines an accommodation chamber extending along a central axis, and has a partition wall separating the accommodation chamber into front and rear chambers. The rear chamber has an internal duct. The front chamber has a central region and a surrounding region that are radially opposite to each other. An inlet is disposed forwardly of the front chamber and upstream of the central region. An outlet is disposed downstream of the surrounding region. The canister member is disposed in the rear chamber to separate the rear chamber into stator-side and rotor-side spaces. The canister member includes a front tubular end secured to the partition wall, and a rear end wall which extends radially to interrupt fluid communication between the stator-side space and the internal duct, and which has an entry duct in fluid communication with the internal duct. The fluid drawing mechanism includes a stator disposed in the stator-side space, a hollow shaft which is disposed in the rotor-side space, which has an output spindle extending into the central region, and which defines a passage extending along the central axis to communicate the internal duct with the central region, a rotor which is mounted in the rotor-side space to rotate the outer spindle, and an impeller which is mounted in the central region to be rotated with the output spindle so as to compel the working fluid introduced through the inlet to flow towards the surrounding region and out of the outlet. The auxiliary conduit has an in-flow port disposed upstream of the central region and downstream of the inlet, and extends to be communicated with the internal duct so as to divert part of the introduced the working fluid to directly flow through the internal duct and the passage and out of the output spindle, thereby diffusing heat that is generated as a result of rotation of the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment of the invention, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of the preferred embodiment of a fluid pump according to this invention;

FIG. 2 is a perspective view of the preferred embodiment when viewed from another angle; and

FIG. 3 is a sectional view of the preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 to 3, the preferred embodiment of a fluid pump according to the present invention is provided for delivering cooled working fluid in an engine cooling system (not shown), and is shown to comprise a housing unit 3, a canister member 4, a fluid drawing mechanism 6, and an auxiliary conduit 7.

The housing unit 3 defines an accommodation chamber 30 extending along a central axis. Specifically, the housing unit 3 includes a rear peripheral wall 31 which surrounds a central axis, a rear mount wall 32 which extends radially and which has an internal duct 321 that extends therethrough along the central axis, a partition wall 33 which is watertightly connected to the rear peripheral wall 31 and which extends radially so as to cooperate with the rear peripheral wall 31 and the rear mount wall 32 to define a rear chamber 302, and a cover 34 which has a surrounding wall 341 that is connected to the partition wall 33, that extends forwardly and towards the central axis to terminate at an inlet 501, and that cooperates with the partition wall 33 to define a front chamber 301. The front chamber 301 has a central region 303 and a surrounding region 304 that are disposed radially opposite to each other. Preferably, the surrounding region 304 is configured to extend spirally relative to the central axis from the central region 303 and to terminate at an outlet 502. Thus, the inlet 501 is disposed forwardly of the front chamber 301 and upstream of the central region 303. The outlet 502 is disposed downstream of the surrounding region 304. Furthermore, the partition wall 33 has an annular bearing wall 331 surrounding the central axis.

The canister member 4 is disposed in the rear chamber 302, and is configured to watertightly separate the rear chamber 302 into stator-side and rotor-side spaces 305, 306. The canister member 4 includes a front tubular end 43 which is secured to the partition wall 33, and a rear end wall 41 which extends radially to interrupt fluid communication between the stator-side space 305 and the internal duct 321, and which has an entry duct 411 that extends along the central axis to be in fluid communication with the internal duct 321.

The fluid drawing mechanism 6 includes a stator 61, a hollow shaft 62, a rotor 63, and an impeller 67. The stator 61 is disposed in the stator-side space 305 and is controlled by a control unit 66 in a known manner. The hollow shaft 62 is disposed in the rotor-side space 306, and has front and rear journalled ends 621, 622 mounted rotatably and respectively on the annular bearing wall 331 and the rear end wall 41 about the central axis through bearing units 64, 65 so as to be prevented from moving axially. The front jounalled end 621 further extends into the central region 303 to serve as an output spindle 624. The hollow shaft 62 defines a passage 620 extending along the central axis to communicate the internal duct 321 with the central region 303. The rotor 63 is received in the rotor-side space 306, and is mounted on the hollow shaft 62 to rotate the outer spindle 624 about the central axis. The impeller 67 is received in the central region 303 and is mounted on the output spindle 624 to be rotated with the output spindle 624. Thus, when power is supplied to the fluid pump, the stator 61 generates a magnetic field which causes the rotor 63 and the hollow shaft 62 to rotate. The rotation of the hollow shaft 62 drives the impeller 67 so that the cooled working fluid introduced through the inlet 501 is compelled to flow towards the surrounding region 304 and out through the outlet 502.

The auxiliary conduit 7 includes a rear segment 71 which is disposed rearwardly of the rear mount wall 32 of the housing unit 3, and which extends radially to be in fluid communication with the internal duct 321, an elongated segment 72 which extends forwardly from the rear segment 71 along the rear peripheral wall 31, and a front segment 73 which is disposed on the surrounding wall 341 of the cover 34 and which extends forwardly of the surrounding region 304 and below the inlet 501. The front segment 73 further extends toward the central axis and defines an in-flow port 730 that is in fluid communication with the inlet 501. Thus, the auxiliary conduit 7 is disposed upstream of the central region 303 and downstream of the inlet 501, and is communicated with the internal duct 321.

During rotation of the impeller 67, when the cooled working fluid is introduced into the central region 303, part of the introduced cooled working fluid will be drawn by a negative pressure suction force generated within the auxiliary conduit 7 and the passage 620 to directly flow through the in-flow port 730, the auxiliary conduit 7, the internal duct 321, the entry duct 411, and the passage 620, and out of the output spindle 624 so as to flow back into the central region 303, where it is mixed with the relatively low-temperature cooled working fluid present in the central region 303 before flowing out through the outlet 502. Therefore, by passing part of the cooled working fluid through the passage 620, heat generated as a result of the rotation of the rotor 63 can be diffused and the temperature of the fluid pump can be lowered.

As illustrated in the following table, when the temperature of the working fluid passing through the inlet 501 is 80° C., the temperature around the control unit 66 in this invention will be 86.1° C. (about 359.1° K) which is comparatively lower than 92.6° C. (about 365.6° K), the temperature around the controller of the aforementioned conventional fluid pump.

Pump of this invention Conventional Pump Time (sec) Temperature (° K) Time (sec) Temperature (° K) 0 0 0 0 1.9913816E−03 0 1.9913816E−03 0 3.9271740E−03 7.1896209E−09 3.9271740E−03 9.1314355E−08 6.0127615E−03 2.9321601E+02 6.0127615E−03 2.1237245E+02 8.2076415E−03 3.3627246E+02 8.2076415E−03 3.3615823E+02 1.0071468E−03 3.4574462E+02 1.0071468E−03 3.4986239E+02 1.1728488E−03 3.4999071E+02 1.1728488E−03 3.5319681E+02 1.4351077E−03 3.5562096E+02 1.4351077E−03 3.6123448E+02 1.5867259E−03 3.5705531E+02 1.5867259E−03 3.6317741E+02 1.8437840E−03 3.5830933E+02 1.8437840E−03 3.6531281E+02 2.0372916E−03 3.5911732E+02 2.0372916E−03 3.6557956E+02

As illustrated, by means of the auxiliary conduit 7 which is disposed outwardly of the rear peripheral wall 31, part of the cooled working fluid can flow into the passage 620 in the hollow shaft 62 from the exterior of the housing unit 3 so that this part of the fluid is kept relatively cool before entering the passage 620. Hence, during operation of the fluid pump of this invention, relatively cool fluid can circulate within the interior of the housing unit 3 to dissipate heat around the control unit 66, the stator 61 and the hollow shaft 62 so as to efficiently and rapidly lower the temperature around the control unit 66, thereby prolonging the service life of the fluid pump. Moreover, since the fluid can be kept in a relatively cool state, the heat dissipating efficiency of the fluid pump can be enhanced.

While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretations and equivalent arrangements. 

1. A fluid pump for delivering cooled working fluid in an engine cooling system, said fluid pump comprising: a housing unit defining an accommodation chamber which extends along a central axis, and having a partition wall which extends radially to watertightly separate said accommodation chamber into front and rear chambers, said rear chamber having a rear peripheral wall which surrounds the central axis, and a rear mount wall which extends radially and which has an internal duct that extends therethrough along the central axis, said front chamber having a central region and a surrounding region that are disposed radially opposite to each other; an inlet which is disposed forwardly of said front chamber and upstream of said central region; an outlet which is disposed downstream of said surrounding region; a canister member disposed in said rear chamber, and configured to watertightly separate said rear chamber into stator-side and rotor-side spaces, said canister member including a front tubular end which is secured to said partition wall, and a rear end wall which extends radially to interrupt fluid communication between said stator-side space and said internal duct, and which has an entry duct that extends along the central axis to be in fluid communication with said internal duct; a stator which is disposed in said stator-side space; a hollow shaft which is disposed in said rotor-side space and which has an output spindle that extends into said central region, said hollow shaft defining a passage which extends along the central axis to communicate said internal duct with said central region; a rotor which is mounted in said rotor-side space to rotate said outer spindle about the central axis; an impeller which is mounted in said central region to be rotated with said output spindle, and which is configured to compel the cooled working fluid introduced through said inlet to flow towards said surrounding region and out through said outlet when said impeller is rotated with said output spindle; and an auxiliary conduit which has an in-flow port that is disposed upstream of said central region and downstream of said inlet, and which extends to be in fluid communication with said internal duct so as to divert part of the introduced cooled working fluid to directly flow through said internal duct and said passage and out of said output spindle, thereby diffusing heat that is generated as a result of rotation of said rotor.
 2. The fluid pump according to claim 1, wherein said surrounding region is configured to extend spirally relative to the central axis from said central region and to terminate at said outlet.
 3. The fluid pump according to claim 1, wherein said auxiliary conduit includes a rear segment which is disposed rearwardly of said rear mount wall of said housing unit, and which extends radially to be in fluid communication with said internal duct, an elongated segment which extends forwardly from said rear segment along said rear peripheral wall, and a front segment which extends toward the central axis from said elongated segment and which defines said in-flow port, said in-flow port being in fluid communication with said inlet.
 4. The fluid pump according to claim 3, wherein said housing unit has a cover which has a surrounding wall that is connected to said partition wall, that extends forwardly and towards the central axis to terminate at said inlet, and that cooperates with said partition wall to define said front chamber, said front segment of said auxiliary conduit being disposed on said surrounding wall and extending forwardly of said surrounding region and below said inlet to define said in-flow port of said auxiliary conduit.
 5. The fluid pump according to claim 1, wherein said partition wall has an annular bearing wall which surrounds the central axis, said hollow shaft having front and rear journalled ends that are mounted rotatably and respectively on said annular bearing wall and said rear end wall about the central axis, said front jounalled end extending into said central region to serve as said output spindle. 